The key message is the importance of a systemic approach to handling water and energy together, both in design and in operation. The paper demonstrates how renewable energy, solar photovoltaic (PV) and solar thermal, in combination with a small nutrient removal plant provides a reliable solution for small-scale decentralized water recovery operations. The system is automated and can operate outside the power grid and is designed to be a fully circular system in terms of both energy and water. The system has been installed on an island in the archipelago outside Stockholm, Sweden, to replace an old-fashioned septic tank. The effluent must satisfy rather strict effluent quality criteria for the Baltic Sea. The paper describes design considerations, instrumentation aspects, automation features, and operation experiences.

  • The key message is the importance of a systemic approach to handling water and energy together, both in design and in operation. The paper demonstrates how renewable energy, solar PV and solar thermal, in combination with a small nutrient removal plant provides a reliable solution for small-scale decentralized water recovery operations.

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